There is a constant search in the area of elastomeric polymers, such as styrene-butadiene rubbers, to control Mooney viscosity. Note, for example U.S. Pat. Nos. 5,659,056; 6,255,404; 6,393,167; 7,342,070; and published patent application No. 2009/0163668, the disclosures of which are incorporated by reference. Mooney viscosity creep with aging has become even more pronounced with the movement from batch to continuous polymerization.
Advantageous properties have been imparted to polymers which are typically terminated using a number of different functional compounds, including silane containing compounds, to yield silane end-capped polymers. Note also, for example, U.S. Pat. Nos. 3,244,664 and 4,185,042, the disclosures of which are incorporated by reference. This alkoxysilane termination may also result in an increase in the Mooney viscosity of the treated polymer. However, upon the subsequent process of desolventization of the alkoxysiloxane terminated polymers through the use of either steam or heated water, an even larger increase in Mooney viscosity often occurs during the hydrolysis of the alkoxysiloxane end groups such as pendant —SiOR groups on the siloxane end groups, thereby leading to coupling of the polymer via formation of Si—O—Si bonds between two end groups. Accordingly, many of the processes tried in the past do not actually prevent an increase in Mooney viscosity, but only slow the rate of the hydrolysis reaction and, therefore, the rate of coupling of the polymer. Over a period of time, for example during storage, the slow hydrolysis of the end groups will occur, thereby continuing the problem of increased Mooney viscosity and coupling of the alkoxysilane terminated polymers with aging.
Thus, while attempts have been made to reduce the rate of the hydrolysis reaction that results in the coupling of the alkoxysilane end groups of the polymers, the art has not provided a means or method by which to stabilize the polymer upon aging and essentially stop or slow down the coupling of the alkoxysilane terminated polymers over time.